1. Field of the Invention
This invention relates to preliminary processing of cured tobacco leaves for the purpose of making them into tobacco products such as filler for cigarettes.
2. Description of the Prior Art
The processing of tobacco leaves as conventionally practiced involves the treatment of the cured dry leaves by a stripping or threshing operation in a machine which separates the stem portion from the lamina. The tobacco leaves are brought into the stemmery factory in bundles referred to as "hands." Each hand consists of a plurality of leaves oriented so that the tips and butts of the leaves are at opposite extremities of the bundle. Another tobacco leaf, referred to as a "tie-leaf" is wrapped around the butt extremity with the free end of the tie-leaf tucked in between the butts of two adjacent leaves, said tie-leaf having been earlier applied to hold the bundle intact during curing of the leaves.
The hands, which may be of non-uniform length, are separately deposited upon a feed-in conveyor belt leading to a stemming machine, forming a substantially parallel array wherein the butt extremities are directed toward the same edge of the belt and the tip extremities are properly positioned at the opposite edge of the belt for severance or "tipping." The tips of the leaves, which may represent almost half the leaf, are processed separately from the rest of the leaves, thereby reducing unnecessary breakage and damage to the lamina in the tips that would be caused by threshing.
Several general techniques have been employed for separating the individual leaves of the hand on the feed-in belt before entering the stemming machine. In one technique, the butt extremities, containing the tie leaf are transversely severed and routed to a separate processing operation. In another technique, as described in British Patent 2,290,694 to Silva, the tie leaves are cut by passage of the butt extremity between opposed cylinders having a multitude of axially parallel blades that are forced into the tie leaves of the bundles. One advantage of the use of blade-holding cylinders is that the elongated blades cover a large lateral zone of the width of the belt. This more assuredly contacts the butt extremities which are not aligned with respect to the edge of the belt. The interactive cylinders further prevent any obstructing-type of accumulation of bundles upon the belt awaiting the tie-leaf removal operation. A problem, however, with Silva's cylinder-mounted blade technique is that it's pressing mechanism of cutting is inefficient, requiring extremely sharp blades and rigorous monitoring of rotational speed and cylinder force.
Another method for separating the leaves of the hands on the feed-in belt is described in U.S. Pat. No. 2,055,307 to Priddy wherein a series of blades radially emergent from shafts parallel to the running direction of the belt cut the tie leaf in a path aligned with the long axis of the bundle. The direction of rotation of the blades is such that the cutting edge of the blade, at the instant of contact with the tie leaf, is travelling away from the tip extremity and toward the butt extremity of the hand. Although the Priddy apparatus represents an efficient cutting mechanism, the effective or "footprint" zone on the belt is very narrow. Accordingly, hands which are slightly misaligned on the belt might be skipped by the rotating blades.
It is to be further noted that, in both the Silva and Priddy approaches to leaf separation, the butt extremities of the hands are acted upon from both above and below. This requires that the butt extremities of the hands are unsupported from beneath while nevertheless continuing their advancement toward the thresher. This is accomplished in the Priddy apparatus by the use of three separate advancing belts plus an advancing chain disposed in a tie-removing region between two of said belts. Silva similarly employs an advancing chain to carry the hands away from a conveyor belt and through a tie-removing region. Such specialized carrying and advancing means require careful synchronization of the several interactive features, and contributes further to the complexity of the apparatus.
The use of rotating drums positioned at an angled relationship to an advancing series of tobacco hands is disclosed in U.S. Patent to Michaux, wherein vertically hung hands are cleaned of debris by passage between two drums having beater cloths.
It is accordingly an object of the present invention to provide apparatus for removing tie elements from the butt extremities of sequential hands of tobacco being transported upon a moving belt.
It is another object of this invention to provide apparatus as in the foregoing object which cuts said tie elements within a relatively wide lateral zone on said belt.
It is a further object of the present invention to provide apparatus of the aforesaid nature which prevents accumulation of hands upstream of the cutting mechanism.
Still further objects of this invention are to provide apparatus of the aforesaid nature of reliable performance and relatively simple construction amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.